Laser radar optical axis on-line calibration system and optical axis on-line calibration method thereof

Abstract

The invention relates to a laser radar optical axis on-line calibration system, which comprises a laser light source, an APD receiving device arranged on the laser light source, a collimator arranged on one side of the laser light source, a first beam splitter prism and a second beam splitter prism arranged in one end of the collimator, and an off-axis parabolic mirror arranged in the other end of the collimator, a plane mirror is arranged in the collimator, a diffuse reflection plate is arranged below the plane mirror, a first camera is arranged in the collimator and located below the second beam splitter prism, and a light supplementing lamp source is arranged above the second beam splitter prism. The camera is combined with the beam splitter prism, real-time visual monitoring of laser spots is achieved, online visual calibration of the optical axis is achieved, the optical axis calibration efficiency can be greatly improved, an off-axis reflection type optical path structure is adopted, the calibration device is compact in structure, space is saved, and the installation and adjustment space can be reduced.

Description

Technical Field

[0001] The present invention belongs to the technical field of laser radar, and in particular relates to a laser radar optical axis online calibration system and an optical axis online calibration method thereof. Background Art

[0002] Lidar is a radar system that emits laser beams to detect the position, speed and other characteristic quantities of a target. Its working principle is to transmit a detection signal to the target, and then compare the received signal reflected from the target with the transmitted signal. After appropriate processing, relevant information about the target can be obtained, such as target distance, direction, height, speed, attitude, and even shape parameters, so as to detect, track and identify targets such as aircraft and missiles. It consists of a laser transmitter, an optical receiver, a turntable and an information processing system. The laser converts electrical pulses into light pulses and transmits them. The optical receiver then restores the light pulses reflected from the target into electrical pulses and sends them to the display. Lidar has a wide range of applications in the fields of autonomous driving and industrial inspection. During its application, there are high requirements for the coaxiality of the laser radar's light receiving and transmitting axes, and it needs to be tested and adjusted with high precision. In the prior art, the laser radar optical axis calibration device mostly uses a detection device such as a reflection vision method to calibrate the optical axis. This type of calibration method has the problems of low efficiency and poor accuracy. Summary of the invention

[0003] Therefore, the present invention aims to solve the problems of low efficiency and poor precision of optical axis calibration in the prior art.

[0004] To this end, the technical solution adopted is that a laser radar optical axis online calibration system of the present invention includes: a laser light source, an APD receiving device is arranged on the laser light source, a collimator is arranged on one side of the laser light source, a first beam splitter prism and a second beam splitter prism are arranged in one end of the collimator, an off-axis parabolic reflector is arranged in the other end of the collimator, a plane reflector is arranged in the collimator, a diffuse reflection plate is arranged below the plane reflector, a first camera is arranged in the collimator below the second beam splitter prism, and a fill light source is arranged above the second beam splitter prism;

[0005] The laser light emitted by the laser light source is reflected by the off-axis parabolic reflector. The laser light reflected by the plane reflector is diffusely reflected by the diffuse reflection plate. The laser light is reflected by the plane reflector again and enters the off-axis parabolic reflector. The laser light reflected by the off-axis parabolic reflector is transmitted through the second beam splitter prism and the first beam splitter prism in turn, and is received by the APD receiving device, presenting a second light spot on the APD receiving device. At the same time, the fill light emitted by the fill light source is reflected by the second beam splitter prism, and then transmitted through the first beam splitter prism to irradiate the APD receiving device, so as to fill light for the calibration reference light spot on the APD receiving device and the received second light spot. After the fill light, the calibration reference light spot and the second light spot are reflected by the first beam splitter prism and then received by the first camera, and it is determined whether the calibration reference light spot and the second light spot received by the first camera are coaxial. If not, the angle at which the laser light is emitted by the laser light source is adjusted until the second light spot and the calibration reference light spot are coaxial.

[0006] Preferably, a second camera is arranged on the collimator below the diffuse reflection plate.

[0007] Preferably, the diffuse reflection plate is a paper target.

[0008] Preferably, the fill light source is an incandescent lamp.

[0009] Preferably, the off-axis parabolic reflector is fixed in the reflector frame by a pressing ring, and the reflector frame and the collimator are connected by screws.

[0010] An optical axis online calibration method, used to adjust a laser radar optical axis online calibration system, comprises the following steps:

[0011] Step 1: Turn on the laser light source, and the emitted laser enters the collimator, is reflected by the off-axis parabolic reflector, and then is diffusely reflected by the diffuse reflector, presenting a first light spot on the surface of the diffuse reflector;

[0012] Step 2: observe the position of the first light spot through the second camera, and adjust the laser emission angle of the laser light source so that the first light spot is at the center of the second camera screen;

[0013] Step 3: After the laser is diffusely reflected by the diffuse reflection plate, the laser is reflected by the plane reflector again and enters the off-axis parabolic reflector. The laser line reflected by the off-axis parabolic reflector is transmitted through the second beam splitter prism and the first beam splitter prism in sequence, and is received by the APD receiving device, presenting a second light spot on the APD receiving device.

[0014] Step 4: At the same time, the fill light emitted by the fill light source is reflected by the second beam splitter prism, and then transmitted through the first beam splitter prism to illuminate the APD receiving device, thereby providing fill light for the calibration reference light spot on the APD receiving device and the received second light spot;

[0015] Step 5: After the calibration reference light spot and the second light spot are filled with light, they are reflected by the first beam splitter prism and received by the first camera. It is determined whether the calibration reference light spot and the second light spot received by the first camera are coaxial. If not, adjust the angle at which the laser light source emits the laser until the second light spot and the calibration reference light spot are coaxial.

[0016] The technical solution of the present invention has the following advantages: by combining a camera with a dichroic prism, real-time visual monitoring of the laser spot is realized, and the optical axis is calibrated online visually, which can greatly improve the efficiency of optical axis calibration. In addition, an off-axis reflective optical path structure is adopted, and the calibration device has a compact structure, saves space, and can reduce the installation space.

[0017] Other features and advantages of the present invention will be described in the following description, and partly become apparent from the description, or understood by practicing the present invention. The purpose and other advantages of the present invention can be realized and obtained by the structures particularly pointed out in the written description and the accompanying drawings.

[0018] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The accompanying drawings are used to provide a further understanding of the present invention and constitute a part of the specification. Together with the embodiments of the present invention, they are used to explain the present invention and do not constitute a limitation of the present invention. In the accompanying drawings:

[0020] Figure 1 It is a schematic diagram of the structure of the present invention;

[0021] Figure 2 It is a schematic diagram of the technical principle of the present invention;

[0022] Description of reference numerals:

[0023] 1. Laser light source; 2. APD receiving device; 3. Collimator; 4. First beam splitter prism; 5. Second beam splitter prism; 6. Off-axis parabolic reflector; 7. Plane reflector; 8. Diffuse reflector; 9. First camera; 10. Second camera; 11. Fill light source. DETAILED DESCRIPTION

[0024] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0025] It should be noted that when a component is referred to as being "fixed to" or "disposed on" another component, it can be directly on the other component or indirectly on the other component. When a component is referred to as being "connected to" another component, it can be directly or indirectly connected to the other component.

[0026] It should be understood that the orientation or position relationship indicated by terms such as "length", "width", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside" and "outside" are based on the orientation or position relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operate in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0027] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0028] The present invention provides a laser radar optical axis online calibration system, such as Figure 1-2 As shown, it includes: a laser light source 1, an APD (Avalanche photodiode) receiving device 2 is arranged on the laser light source 1, the APD receiving device 2 adopts a photoelectric avalanche diode, a collimator 3 is arranged on one side of the laser light source 1, a first beam splitter prism 4 and a second beam splitter prism 5 are arranged in one end of the collimator 3, an off-axis parabolic reflector 6 is arranged in the other end of the collimator 3, a plane reflector 7 is arranged in the collimator 3, a diffuse reflection plate 8 is arranged below the plane reflector 7, a first camera 9 is arranged below the second beam splitter prism 5 in the collimator 3, and a fill light source 11 is arranged above the second beam splitter prism 5; the laser light source 1 is not coaxial with the first beam splitter prism 4 and the second beam splitter prism 5, and the incident laser does not pass through the first beam splitter prism 4 and the second beam splitter prism 5, but is incident on the off-axis parabolic reflector 6. Since the APD receiving device 2 is coaxial with the first beam splitter prism 4 and the second beam splitter prism 5, the outgoing laser will not pass through the first beam splitter prism 4 and the second beam splitter prism 5. The outgoing laser will pass through the top or side of the first beam splitter prism 4 and the second beam splitter prism 5 and enter the collimator 3.

[0029] The laser light emitted by the laser light source 1 is reflected by the off-axis parabolic reflector 6, and then the laser light reflected by the plane reflector 7 is diffusely reflected by the diffuse reflection plate 8. The laser light is then reflected by the plane reflector 7 again and enters the off-axis parabolic reflector 6. The laser light reflected by the off-axis parabolic reflector 6 is transmitted through the second beam splitter prism 5 and the first beam splitter prism 4 in turn, and is received by the APD receiving device 2, presenting a second light spot on the APD receiving device 2. At the same time, the fill light emitted by the fill light source 11 is reflected by the second beam splitter prism 5, and then transmitted through the first beam splitter prism 4 to irradiate the APD receiving device 2, so as to fill light for the calibration reference light spot on the APD receiving device 2 and the received second light spot. After the fill light, the calibration reference light spot and the second light spot are reflected by the first beam splitter prism 4 and then received by the first camera 9, and it is determined whether the calibration reference light spot and the second light spot received by the first camera 9 are coaxial. If not, the angle at which the laser light is emitted by the laser light source 1 is adjusted until the second light spot and the calibration reference light spot are coaxial.

[0030] A second camera 10 is provided on the collimator 3 below the diffuse reflector 8, and is used to observe the laser spot on the diffuse reflector 8. The diffuse reflector 8 is a paper target, which is light-transmissive and can be observed by the second camera 10. The fill light source 11 is an incandescent lamp, which is used to enhance the light and illuminate the second light spot and the calibration reference light spot. The second light spot and the calibration reference light spot on the APD receiving device 2 are difficult to observe with the naked eye. After illumination, the light is reflected by the first beam splitter prism 4, which is convenient for the first camera 9 to observe. The off-axis parabolic reflector 6 is fixed in the reflector frame by a pressure ring, and the reflector frame is connected to the collimator 3 by screws, which is convenient for the installation and disassembly of the off-axis parabolic reflector 6.

[0031] The working principle and beneficial technical effects of the above technical solution are as follows: the laser light source 1 is turned on, the emitted laser light enters the collimator 3, and after being reflected by the off-axis parabolic reflector 6, the laser light reflected by the plane reflector 7 is diffusely reflected by the diffuse reflector 8, and a first light spot is presented on the surface of the diffuse reflector 8. The position of the light spot is observed by the second camera 10, and the outgoing laser angle of the laser light source 1 is adjusted so that the first light spot is at the center position of the screen of the second camera 10, and the outgoing laser light is roughly adjusted. After the laser light is diffusely reflected by the diffuse reflector 8, the laser light is reflected again by the plane reflector 7 to enter the off-axis parabolic reflector 6, and the laser light reflected by the off-axis parabolic reflector 6 is transmitted through the second diffuser 10 in sequence. The light prism 5 and the first beam splitter prism 4 are received by the APD receiving device 2, and a second light spot is presented on the APD receiving device 2; at the same time, the fill light emitted by the fill light source 11 is reflected by the second beam splitter prism 5, and then transmitted through the first beam splitter prism 4, and irradiated onto the APD receiving device 2, so as to fill light for the calibration reference light spot and the received second light spot on the APD receiving device 2. After the fill light, the calibration reference light spot and the second light spot are reflected by the first beam splitter prism 4 and then received by the first camera 9, and it is determined whether the calibration reference light spot and the second light spot received by the first camera 9 are coaxial. If they are not coaxial, the angle at which the laser light source 1 emits the laser is adjusted until the second light spot and the calibration reference light spot are coaxial. By combining the camera with the beam splitter prism, real-time visual monitoring of the laser light spot is realized, and the optical axis is calibrated online visually, which can greatly improve the efficiency of optical axis calibration, and adopts an off-axis reflective optical path structure, so that the calibration device has a compact structure, saves space, and can reduce the installation space.

[0032] In one embodiment, an optical axis online calibration method is used to adjust a laser radar optical axis online calibration system, comprising the following steps:

[0033] Step 1, turn on the laser light source 1, the emitted laser enters the collimator 3, is reflected by the off-axis parabolic reflector 6, and then is reflected by the plane reflector 7 and diffusely reflected by the diffuse reflector 8, and presents a first light spot on the surface of the diffuse reflector 8;

[0034] Step 2: observe the position of the first light spot through the second camera 10, and adjust the angle of the laser light emitted by the laser light source 1 so that the first light spot is at the center of the screen of the second camera 10;

[0035] Step 3: After the laser is diffusely reflected by the diffuse reflection plate 8, the laser is reflected again by the plane reflector 7 and enters the off-axis parabolic reflector 6. The laser light reflected by the off-axis parabolic reflector 6 is transmitted through the second beam splitter prism 5 and the first beam splitter prism 4 in sequence, and is received by the APD receiving device 2, presenting a second light spot on the APD receiving device 2.

[0036] Step 4: At the same time, the fill light emitted by the fill light source 11 is reflected by the second beam splitter prism 5, and then transmitted through the first beam splitter prism 4 to irradiate the APD receiving device 2, so as to provide fill light for the calibration reference light spot and the received second light spot on the APD receiving device 2;

[0037] Step 5: After the calibration reference light spot and the second light spot are filled with light, they are reflected by the first beam splitter prism 4 and received by the first camera 9. It is determined whether the calibration reference light spot and the second light spot received by the first camera 9 are coaxial. If not, adjust the angle at which the laser light source 1 emits the laser until the second light spot and the calibration reference light spot are coaxial.

[0038] Beneficial technical effects of the above technical solution: Through the above optical axis online calibration method, real-time monitoring and visual calibration of the laser optical axis can be achieved. The compact structure and visual real-time monitoring can greatly improve the efficiency and accuracy of optical axis calibration. In addition, the reflective optical path structure is compact, which can reduce the space occupied by the laser radar optical axis calibration, making its application scenarios more extensive.

[0039] Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include these modifications and variations.

Claims

1. A laser radar optical axis online calibration system, characterized in that: include: A laser light source (1), an APD receiving device (2) is arranged on the laser light source (1), a collimator (3) is arranged on one side of the laser light source (1), a first beam splitter prism (4) and a second beam splitter prism (5) are arranged in one end of the collimator (3), an off-axis parabolic reflector (6) is arranged in the other end of the collimator (3), a plane reflector (7) is arranged in the collimator (3), a diffuse reflection plate (8) is arranged below the plane reflector (7), a first camera (9) is arranged in the collimator (3) below the second beam splitter prism (5), and a fill light source (11) is arranged above the second beam splitter prism (5); The laser light emitted by the laser light source (1) is reflected by the off-axis parabolic reflector (6), and then the laser light reflected by the plane reflector (7) is diffusely reflected by the diffuse reflection plate (8). The laser light is then reflected by the plane reflector (7) again and enters the off-axis parabolic reflector (6). The laser light reflected by the off-axis parabolic reflector (6) is transmitted through the second beam splitter prism (5) and the first beam splitter prism (4) in sequence, and is received by the APD receiving device (2), presenting a second light spot on the APD receiving device (2). At the same time, the fill light light emitted by the fill light source (11) is reflected by the second beam splitter prism (5), and then transmitted through the first beam splitter prism (4), and irradiated onto the APD receiving device (2), so as to provide fill light for the calibration reference light spot and the received second light spot on the APD receiving device (2). The calibration reference light spot and the second light spot are reflected by the first beam splitter prism (4) after being supplemented with light and then received by the first camera (9). It is determined whether the calibration reference light spot and the second light spot received by the first camera (9) are coaxial. If they are not coaxial, the angle at which the laser light source (1) emits the laser is adjusted until the second light spot and the calibration reference light spot are coaxial.

2. The laser radar optical axis online calibration system according to claim 1, characterized in that: A second camera (10) is arranged on the collimator (3) below the diffuse reflection plate (8).

3. The laser radar optical axis online calibration system according to claim 1, characterized in that: The diffuse reflection plate (8) is a paper target.

4. The laser radar optical axis online calibration system according to claim 1, characterized in that: The fill light source (11) is an incandescent lamp.

5. The laser radar optical axis online calibration system according to claim 1, characterized in that: The off-axis parabolic reflector (6) is fixed in the reflector frame via a pressing ring, and the reflector frame is connected to the collimator (3) via screws.

6. An optical axis online calibration method, used to adjust a laser radar optical axis online calibration system according to any one of claims 1 to 5, characterized in that: The steps include: Step 1: Turn on the laser light source (1), and the emitted laser light enters the collimator (3), is reflected by the off-axis parabolic reflector (6), and then is reflected by the plane reflector (7). The laser light is diffusely reflected by the diffuse reflector (8), and a first light spot is presented on the surface of the diffuse reflector (8); Step 2: observing the position of the first light spot through the second camera (10), and adjusting the angle of the laser light emitted by the laser light source (1) so that the first light spot is located at the center of the screen of the second camera (10); Step 3: After the laser is diffusely reflected by the diffuse reflection plate (8), the laser is reflected again by the plane reflection mirror (7) and enters the off-axis parabolic reflection mirror (6). The laser light reflected by the off-axis parabolic reflection mirror (6) is transmitted through the second beam splitter prism (5) and the first beam splitter prism (4) in sequence, and is received by the APD receiving device (2), presenting a second light spot on the APD receiving device (2); Step 4: The fill light emitted by the fill light source (11) is reflected by the second beam splitter prism (5), then transmitted through the first beam splitter prism (4), and irradiated onto the APD receiving device (2), thereby providing fill light for the calibration reference light spot and the received second light spot on the APD receiving device (2); Step 5: After the calibration reference light spot and the second light spot are supplemented with light, they are reflected by the first beam splitter prism (4) and then received by the first camera (9). It is determined whether the calibration reference light spot and the second light spot received by the first camera (9) are coaxial. If they are not coaxial, the angle at which the laser light source (1) emits the laser is adjusted until the second light spot and the calibration reference light spot are coaxial.

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